Plug-in hybrid electric vehicle secondary cooling system

ABSTRACT

A system for utilizing heat generated by a component of a plug-in hybrid electric vehicle includes a first component having a first coolant system extending therethrough. The first coolant circulation system includes a first radiator. The system also includes a second component having a second coolant circulation system extending therethrough. The second coolant circulation system is in fluid communication with the first coolant circulation system. The first coolant system is configured is to selectively direct heated coolant from the first component to the second component.

BACKGROUND

1. Field

Embodiments of the present invention relate to the utilization of heatgenerated by a first component in a plug-in hybrid electric vehicle toraise the temperature of a second component in a plug-in hybrid electricvehicle.

2. Background Art

Plug-in hybrid electric vehicles are configured to run for apredetermined distance or period of time primarily using energy storedin the vehicle's rechargeable battery. Plug-in hybrid electric vehiclesinclude an internal combustion engine, an electric motor, and arechargeable battery.

Plug-in hybrid electric vehicles are commonly configured in one of twodistinct configurations. In a first configuration, the internalcombustion engine and the electric motor are each configured to delivertorque to the drive wheels of the vehicle. This is known as a blended orparallel configuration. In a second configuration, known as a seriesconfiguration, only the electric motor delivers torque to the drivewheels of the vehicle. In a series configuration, the internalcombustion engine is used exclusively to recharge the rechargeablebattery or to deliver energy to the electric motor.

Both types of plug-in hybrid electric vehicles operate during an initialperiod of time using primarily the energy stored in the rechargeablebattery to run the electric motor and deliver torque to the vehicle'sdrive wheels. During such periods of battery powered operation, theelectric motor may lack sufficient power to meet driver demands. Forinstance, when accelerating on an on ramp to a freeway, the driver maydemand more power from the vehicle's propulsion system than can besupplied by the electric motor powered by the battery alone. Duringthese brief periods of high power demand, the internal combustion enginemay temporarily turn on to provide either additional torque to the drivewheels or additional power to the electric motor to fulfill the demandfor additional power. Once the need for increased power abates, theinternal combustion engine will turn off and will remain off untileither the next demand for increased power or until the rechargeablebattery is drained to the point where continuous operation of theinternal combustion engine is needed.

During battery-only vehicle operations, because the internal combustionengine is operated for only brief, intermittent periods of time, theinternal combustion engine remains well below its optimal operatingtemperature which, depending upon the engine, can vary between 180° and220° F. or even higher. When an internal combustion engine operates at atemperature below its optimal or desirable operating temperature, theinternal combustion engine is less efficient and consumes more fuel.Hence, operation of the internal combustion engine below its optimaloperating temperature can have an adverse impact on the plug-in hybridelectric vehicle's fuel economy. Embodiments of the invention disclosedherein address this and other problems.

SUMMARY

Various embodiments of a system for utilizing heat generated by acomponent of a plug-in hybrid electric vehicle are disclosed herein. Ina first embodiment, the system comprises a first component having afirst coolant circulation system extending therethrough. The firstcoolant circulation system includes a first radiator. The system furthercomprises a second component having a second cooling circulation systemextending therethrough. The second coolant circulation system is influid communication with the first coolant circulation system. In thisfirst embodiment, the first coolant circulation system is configured toselectively direct heated coolant from the first component to the secondcomponent.

In an implementation of the first embodiment, the first coolant systemis further configured to selectively prevent the heated coolant fromflowing between the first component and the first radiator. In avariation of this implementation, the first coolant system furthercomprises a first valve that is configured to selectively direct theflow of heated coolant from the first component to one of the secondcomponent and the first radiator. In another variation, the firstcoolant system is further configured to permit the heated coolant toflow from the first component to the first radiator and to prevent theheated coolant from flowing to the second component when the secondcomponent reaches a predetermined temperature.

In a second embodiment, the system comprises an electric componenthaving a first coolant circulation system extending therethrough. Thefirst coolant circulation system includes a first radiator. The systemfurther comprises an internal combustion engine (ICE) having a secondcoolant circulation system extending therethrough. The second coolantcirculation system is in fluid communication with the first coolantcirculation system. In this second embodiment, the first coolantcirculation system is configured to selectively direct heated coolantfrom the electric component to the ICE.

In an implementation of the second embodiment, the electric componentcomprises an ISC.

In another implementation of the second embodiment, the first coolantsystem is further configured to selectively prevent the heated coolantfrom flowing between the electric component and the first radiator. In avariation of this implementation, the first coolant system furthercomprises a first valve that is configured to selectively direct theflow of the heated coolant from the electric component to one of the ICEand the first radiator. In a further variation, the second coolantcirculation system further comprises a second radiator and a secondvalve configured to selectively direct the flow of coolant from theinternal combustion engine to one of the electric component and thesecond radiator.

In a further variation of this implementation, the second valve isfurther configured to direct the flow of coolant from the internalcombustion engine to the electric component when the first valve directsthe heated coolant from the electric component to the ICE. In a furthervariation, the second valve is further configured to direct the flow ofcoolant from the internal combustion engine to the second radiator whenthe first valve directs the heated coolant from the electric componentto the first radiator. In another variation, the first valve is furtherconfigured to direct the heated coolant from the electric component tothe ICE when the ICE is not operating. The first valve is furtherconfigured to direct the heated coolant from the electric component tothe ICE when the ICE is operating.

In a third embodiment, the system comprises an electric component havinga first coolant circulation system extending therethrough. The firstcoolant circulation system includes a first radiator. The system furthercomprises a heater core having a second coolant circulation systemextending therethrough. The second coolant circulation system is influid communication with the first coolant circulation system. In thisthird embodiment, the first coolant circulation system is configured toselectively direct heated coolant from the first component to the heatercore.

In an implementation of the third embodiment, the electric componentcomprises an ISC.

In another implementation of the third embodiment, the first coolantsystem is further configured to selectively prevent the heated coolantfrom flowing between the electric component and the first radiator.

In another implementation of the third embodiment, the system furthercomprises an internal combustion engine having the second coolantcirculation system extending therethrough. The second coolantcirculation system further comprises a second radiator. In a variationof this implementation, the first coolant system further comprises afirst valve that is configured to selectively direct the flow of theheated coolant from the electric component to one of the second coolantcirculation system and the first radiator. In a further variation ofthis implementation, the second coolant system further comprises asecond valve that is configured to selectively direct the flow ofcoolant from the internal combustion engine to one of the secondradiator and the electric component. In a still further variation, theheater core is positioned downstream of the internal combustion enginesuch that when the second valve directs the flow of coolant from theinternal combustion engine to the electric component, the coolant passesthrough the core. In yet a further variation, the electric componentcomprises an ISC.

BRIEF DESCRIPTION OF THE DRAWINGS

The description herein makes reference to the accompanying drawingswherein like reference numerals refer to like parts throughout theseveral views, and in which:

FIG. 1A is a schematic view illustrating a system for utilizing heatgenerated by an inverter system controller (ISC) to warm an engine blockof an internal combustion engine (ICE) in a plug-in hybrid electricvehicle;

FIG. 1B is a schematic view illustrating the system of FIG. 1A withheated coolant flowing from the ISC to the ICE and then flowing back tothe ISC;

FIG. 2A is a schematic view illustrating an alternate embodiment of thesystem of FIG. 1 wherein heated coolant from the ISC is used to heat aheater core;

FIG. 2B is a schematic view illustrating the system of FIG. 2A withheated coolant flowing from the ISC to the heater core and then back tothe ISC;

FIG. 3A is a schematic view illustrating another embodiment of thesystem of FIGS. 1A and B wherein heated coolant from the ISC heats boththe ICE and the heater core; and

FIG. 3B is a schematic view illustrating the system of FIG. 3A withheated coolant flowing from the ISC through both the ICE and the heatercore and then back to the ISC.

DETAILED DESCRIPTION OF THE EMBODIMENT(S)

Detailed embodiments of the present invention are disclosed herein;however, it is to be understood that the disclosed embodiments aremerely exemplary of the invention that may be embodied in various andalternative forms. The figures are not necessarily drawn to scale, somefeatures may be exaggerated or minimized to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for the claims and/or as a representative basis forteaching one skilled in the art to variously employ the presentinvention.

Plug-in hybrid electric vehicles include one or more electric motors andone or more internal combustion engines. A rechargeable battery supplieselectric power to the electric motor. An inverter system controller(ISC) converts direct current from the rechargeable battery toalternating current for use by the electric motor. During operations,the temperature of the ISC rises. If not cooled, the ISC will heat to atemperature beyond its optimal operating temperature and may evenoverheat. Similarly, the temperature of the internal combustion engine(ICE) will also rise during normal operations and, if not properlycooled, will exceed an optimal operating temperature for the ICE. Tokeep the ISC cool, the ISC has a first coolant circulation systemextending through the ISC. A coolant having a temperature lower thanthat of the ISC enters the ISC, circulates through the ISC causing thefluid to heat up and the ISC to cool down. The heated fluid is thendirected to a first radiator where the heated fluid is cooled andre-circulated to the ISC.

Similarly, a second coolant circulation system is used to cool the ICE.A fluid having a temperature less than that of the ICE enters the ICE,circulates therethrough and causes the fluid to heat up and the ICE tocool down. The heated fluid exits the ICE and is directed to a secondradiator where the coolant is cooled down and re-circulated back to theICE.

A plug-in hybrid electric vehicle is configured to operate solely onbattery power for a predefined distance or period of time. Duringbattery-only operations, the internal combustion engine is not operatedand an electric motor(s) propels the vehicle. During such periods, therechargeable battery supplies power to the electric motor foroperations. At times where driver or other vehicle demands for powerexceed the power capability of the rechargeable battery power alone, theICE will briefly turn on and operate to assist the electric motors inpropelling the vehicle. During such periods of brief, intermittentoperation, the ICE does not have sufficient time to warm to its optimaloperating temperature (approximately 200° F.). Accordingly, during suchintermittent operations, the ICE operates below its peak efficiencywhich can cause an elevated rate of fuel consumption.

In accordance with the teachings of the present invention, the firstcoolant circulation system is configured to route the heated coolantfrom the ISC to the second coolant circulation system where the heatedcoolant passes through the ICE. The heated coolant is at a temperaturehigher than the ICE and, as the heated coolant passes through the ICE,the ICE acts as a radiator taking heat out of the fluid. This causes theICE to heat up. The second coolant circulation system is configured todirect the cooled coolant exiting the ICE back to the first coolantcirculation system where it is routed through the ISC and the cyclebegins again. In this manner, heat is transferred from the ISC to theICE which permits the ICE to maintain an elevated temperature aboveambient so that the ICE may operate at a higher efficiency level duringthe brief, intermittent periods of operation.

The teachings of the present invention are not limited to using heatedcoolant from the ISC to heat the ICE. Rather, other heat sources andheat targets may be utilized as well. For instance, in anotherembodiment, it may be desirable to route the heated coolant from the ISCthrough a vehicle's heater core which is used to supply heat to avehicle's heating and ventilation system. In this manner, the heatercore, which typically relies on heated coolant routed from the ICE, mayuse heated coolant from the ISC to supply heat to the vehicle's HVACsystem during electric only operations of the plug-in hybrid electricvehicle. In other embodiments, the heated coolant from the ISC may berouted to pass through both the ICE and the heater core. In still otherembodiment, one or more of the electric motors may supply the heatedcoolant instead of the ISC. A greater understanding of the embodimentsof the invention described herein may be obtained through a review ofthe figures accompanying this disclosure together with a review of thedetailed description that follows.

With respect to FIG. 1A, a system 10 for utilizing the heat generated bya component of a plug-in hybrid electric vehicle is schematicallyrepresented. System 10 may be employed in any plug-in hybrid electricvehicle including those configured to operate in both a blended and aseries manner. System 10 includes a first component 12 which generatesheat during operations. In FIG. 1A, first component 12 is depicted as anISC. It should be understood, however, that any heat generatingcomponent may serve as first component 12 of system 10. A first coolantcirculation system 14 circulates a coolant through first component 12.First coolant circulation system 14 includes a first radiator 16,conduits 18 and 20, first radiator 16, conduits 22 and 24, ISC 12, and acoolant pathway internal to ISC 12 (not shown). First coolantcirculation system 14 also includes a first valve 26 which is configuredto route heated coolant exiting from conduit 24 towards one of twodistinct paths. As illustrated in FIG. 1A, first valve 26 is positionedto direct heated coolant from conduit 24 to conduit 18.

System 10 further includes a second component 28. In the embodimentillustrated in FIG. 1A, second component 28 is an ICE. It should beunderstood that second component 28 may be any other component of theplug-in hybrid electric vehicle utilizing system 10 which it would bedesirable to heat.

A second coolant circulation system 30 is configured to cool secondcomponent 28 during operations of second component 28. Second coolantcirculation system 30 comprises a second radiator 32 configured to coolheated coolant as the heated coolant passes through second radiator 32.Second coolant circulation system 30 also includes conduits 34 and 36.Second coolant circulation system 30 also includes conduits 38 and 40.Second coolant circulation system 30 also includes a pathway (not shown)through second component 28 configured to carry coolant throughoutsecond component 28 for the purpose of cooling component 28.

In the embodiment illustrated in FIG. 1A, second coolant circulationsystem 30 further comprises a second valve 42 configured to directheated coolant from conduit 40 towards one of two distinct paths. In theembodiment illustrated in FIG. 1A, second valve 42 is positioned todirect heated coolant to conduit 34 towards second radiator 32.

First coolant circulation system 14 and second coolant circulationsystem 30 are linked in fluid communication with one another throughlinking conduit 44 and linking conduit 46. Linking conduit 44 isconnected to first valve 26 and linking conduit 46 is connected tosecond valve 42. When first valve 26 is moved from the positionillustrated in FIG. 1A to a linking position, first valve 26 will linkconduit 24 with linking conduit 44 and thus allow heated coolant fromfirst component 12 to flow along linking conduit 44 into conduit 38 andfrom there to second component 28. When second valve 42 is moved fromthe position illustrated in FIG. 1A, to a linking position connectingconduit 40 with linking conduit 46, cooled coolant exiting secondcomponent 28 may be directed along linking conduit 46 to conduit 22 andon to first component 12 where the coolant is heated.

With respect to FIG. 1B, the system 10 of FIG. 1A is illustrated withfirst and second valve 26, 42 moved into the linking position. Withfirst and second valve 26, 42 in the linking position, a third coolantcirculation system 48 is formed. In third coolant circulation system 48,coolant enters first component 12 where it is heated and then exitsalong conduit 24, passes through first valve 26 where the heated coolantis directed along linking conduit 44 into conduit 38 and then intosecond component 28. The coolant cools down as it delivers heat tosecond component 28. In this manner, second component 28 serves as aradiator to cool the coolant passing through first component 12. Afterpassing through second component 28, the cooled coolant travels alongconduit 40 into second valve 42 where the coolant is then directed alonglinking conduit 46 to conduit 22 where the coolant is then routed backthrough first component 12 to begin another heating and cooling cycle.With first and second valves 26, 42 in the linking position, first andsecond radiators 16, 32 are bypassed.

First and second valves 26, 42 may be connected to a controller (notshown) which can selectively move first and second valve 26, 42 fromtheir respective independent operation positions to their respectivelinking positions. The controller may be a microprocessor, computer ormechanical device or any other mechanism suitable for controlling thepositions of first and second valve 26, 42 and the timing of theirrespective movement between the independent and linked position. Thecontroller may be configured to control first and second valves 26, 42based on the temperature of ICE 28, or based on whether ICE 28 is on oroff, or based on any other desirable triggering criterion. In otherembodiments, additional valves may be utilized to control the path ofcoolant flow. The controller controlling the positioning of first andsecond valve 26, 42 may be configured to move first and second valves 26and 42 to the linked position while the plug-in hybrid electric vehicleis operating in an electric only mode wherein the internal combustionengine is not operated.

Once the internal combustion engine begins to operate, it will quicklyreach a temperature wherein it can no longer serve as a radiator forcooling the coolant flowing through ISC 12. In normal conventionaloperations, internal combustion engines are operated betweenapproximately 180° and approximately 220° F. while conventional ISC'soperate at a maximum temperature of roughly 160° F. Therefore, once theICE kicks on at the conclusion of electric-only operations and stays on,the controller will move first and second valves 26, 42 from theirrespective linked positions to their independent operation positionswhich closes off ISC 12 from ICE 28 and permits independent operation ofthe first and second coolant circulation systems 14, 30. In someembodiments, ICE 28 may heat slowly and may, for some period of time,continue to serve effectively as a radiator for ISC 12. In suchembodiments, the controller may not move first and second valves 26, 42to their respective independent positions until ICE 28 reaches apredetermined temperature.

With respect to FIG. 2A an alternate embodiment of system 10, heresystem 10′ for utilizing heat generated by a component of a plug-inhybrid electric vehicle is illustrated. In system 10′, a third component50, here illustrated as a heat core, serves as a radiator to cool theheated coolant exiting ISC 12. In FIG. 2A, first valve 26 is illustratedin the independent position wherein first coolant circulation system 14cools ISC 12. System 10′ does not include a second valve 42 or a secondcoolant circulation system 30.

With respect to FIG. 2B, the system 10′ of FIG. 2A is illustrated withfirst valve 26 moved to the linking position to direct coolant from ISC12 to heater core 50. In embodiments of plug-in hybrid electric vehicleswherein heater core 50 is not connected to a coolant system for coolingthe internal combustion engine, ISC 12 may be the sole source of heatfor heater core 50 and the controller controlling first valve 26 maymaintain first valve 26 in the linked position until such time as thetemperature of heater core 50 rises to a level where it can no longereffectively serve as a radiator for ISC 12. In such event, thecontroller would move first valve 26 to the independent position whereinthe coolant passing through ISC 12 would be cooled by first radiator 16.When the temperature of heater core 50 falls below a predeterminedtemperature, the controller may return first valve 26 to the linkedposition to allow coolant to flow from ISC 12 to heater core 50.

With respect to FIG. 3A, a system 10″ for utilizing the heat generatedby a component of a plug-in hybrid electric vehicle is illustrated. Insystem 10″, first coolant circulation system 14 is the same as thatillustrated in FIG. 1A for system 10. In system 10″, second coolantcirculation system 30 circulates coolant through ICE 28 and heater core50. Coolant enters ICE 28 from conduit 38, passes through ICE 28,cooling ICE 28 in the process and exits ICE 28 through conduit 40 whereit is directed into heater core 50. The heated coolant entering heatercore 50 warms heater core 50 as it passes through heater core 50, thenexits heater core 50 and travels along conduit 41 to second valve 42.With second valve 42 in the independent position, the heated coolant isdirected to conduit 34 and then into second radiator 32 where it iscooled and then passes into conduit 36 and then directed into conduit 38where it enters ICE 28 to begin another heating and cooling cycle.

The independent operation of first coolant circulation system 14 andsecond coolant circulation 28 may occur subsequent to an electric onlyoperation of the plug-in hybrid electric vehicle when the internalcombustion engine is operated to aid electric motors in propelling thevehicle. Prior to operation of the internal combustion engine, system10′ operates in the manner depicted in FIG. 3B. A controller (not shown)moves first and second valves 26, 42 to their respective linked positioneffectively bypassing first and second radiators 16 and 32. Asillustrated in FIG. 3B, coolant enters ISC 12 and circulatestherethrough, cooling ISC 12 as it is heated. The coolant exits ISC 12and enters conduit 24 where it is directed to first valve 26. Firstvalve 26, illustrated in the linked position, directs the coolant alonglinking conduit 44 to conduit 38 where it is directed into ICE 28. Theheated coolant passes through ICE 28, warming ICE 28 as it passesthrough and then exits ICE 28 in conduit 40 where it is directed intoheater core 50 where the coolant is further cooled, heating heater core50 in the process. The cooled coolant leaves heater core 50 alongconduit 41 and enters second valve 42 which, when in the linkedposition, directs the coolant into linking conduit 46 where it isdirected to conduit 22 and on into ISC 12 where a new heating andcooling cycle begins. The system 10″ illustrated in FIG. 3B may beutilized during electric-only operations of the plug-in hybrid electricvehicle when ICE 28 is not operated for any substantial length of time.

While embodiments of the invention have been illustrated and described,it is not intended that these embodiments illustrate and describe allpossible forms of the invention. Rather, the words used in thespecification are words of description rather than limitation, andvarious changes may be made without departing from the spirit and scopeof the invention.

1. A system for a hybrid electric vehicle having an engine and anelectric drive system, including an electric motor, the systemcomprising: a component of the electric drive system; a firstclosed-loop coolant circulation system associated with the electricdrive system component and having a coolant configured to flowtherethrough a vehicle component to be heated; a second closed-loopcoolant circulation system associated with the vehicle component to beheated, the first and second coolant circulation systems being operableindependently of each other, and selectively in fluid communication witheach other; such that heated coolant from the component of the electricdrive system can be provided to the vehicle component to be heated; anda radiator in fluid communication with at least one of the closed-loopcoolant circulation systems for transferring heat away from thecorresponding coolant.
 2. The system of claim 1 wherein the firstcoolant circulation system is further configured to selectively preventheated coolant from flowing between the component of the electric drivesystem and the radiator.
 3. The system of claim 2 wherein the firstcoolant circulation system further comprises a first valve configured toselectively direct the flow of heated coolant from the component of theelectric drive system to one of the vehicle component to be heated orthe radiator.
 4. The system of claim 2 wherein the first coolantcirculation system is further configured to permit heated coolant toflow from the component of the electric drive system to the radiator andto prevent heated coolant from flowing to the vehicle component to beheated when the vehicle component to be heated reaches a predeterminedtemperature.
 5. A system for utilizing heat generated by a component ofa plug-in hybrid electric vehicle, the system comprising: an electriccomponent having a first coolant circulation system extendingtherethrough, the first coolant circulation system including a firstradiator; and an internal combustion engine (ICE) having a secondcoolant circulation system extending therethrough, the second coolantcirculation system (ICE) being in fluid communication with the firstcoolant circulation system; wherein the first coolant circulation systemis configured to selectively direct heated coolant from the electriccomponent to the ICE.
 6. The system of claim 5 wherein the electriccomponent comprises an ISC.
 7. The system of claim 5 wherein the firstcoolant system is further configured to selectively prevent the heatedcoolant from flowing between the electric component and the firstradiator.
 8. The system of claim 7 wherein the first coolant systemfurther comprises a first valve configured to selectively direct theflow of the heated coolant from the electric component to one of the ICEand the first radiator.
 9. The system of claim 8 wherein the secondcoolant circulation system further comprises a second radiator and asecond valve configured to selectively direct the flow of coolant fromthe internal combustion engine to one of the electric component and thesecond radiator.
 10. The system of claim 9 wherein the second valve isfurther configured to direct the flow of coolant from the internalcombustion engine to the electric component when the first valve directsthe heated coolant from the electric component to the ICE.
 11. Thesystem of claim 10 wherein the second valve is further configured todirect the flow of coolant from the internal combustion engine to thesecond radiator when the first valve directs the heated coolant from theelectric component to the first radiator.
 12. The system of claim 10wherein the first valve is further configured to direct the heatedcoolant from the electric component to the ICE when the ICE is notoperating and wherein the first valve is further configured to directthe heated coolant from the electric component to the ICE when the ICEis operating.
 13. A system for utilizing heat generated by a componentof a plug-in hybrid electric vehicle, the system comprising: an electriccomponent having a first coolant circulation system extendingtherethrough, the first coolant circulation system including a firstradiator; and a heater core having a second coolant circulation systemextending therethrough, the second coolant circulation system being influid communication with the first coolant circulation system; whereinthe first coolant circulation system is configured to selectively directheated coolant from the first component to the heater core.
 14. Thesystem of claim 13 wherein the electric component comprises an ISC. 15.The system of claim 13 wherein the first coolant system is furtherconfigured to selectively prevent the heated coolant from flowingbetween the electric component and the first radiator.
 16. The system ofclaim 13 further comprising an internal combustion engine having thesecond coolant circulation system extending therethrough, the secondcoolant circulation system further comprising a second radiator.
 17. Thesystem of claim 16 wherein the first coolant system further comprises afirst valve configured to selectively direct the flow of the heatedcoolant from the electric component to one of the second coolantcirculation system and the first radiator.
 18. The system of claim 17wherein the second coolant circulation system further comprises a secondvalve configured to selectively direct the flow of coolant from theinternal combustion engine to one of the second radiator and theelectric component.
 19. The system of claim 18 wherein the heater coreis positioned down stream of the internal combustion engine such thatwhen the second valve directs the flow of coolant from the internalcombustion engine to the electric component, the coolant passes throughthe heater core.
 20. The system of claim 19 wherein the electriccomponent comprises an ISC.